In the field of portable automatic weapons, such as machine guns and pistols, snap or spring mechanisms already exist which permit either a semi-automatic firing, that is, with individual shots, by releasing the trigger after each individual shot, or a fully automatic firing, that is, a rapid firing, by keeping the tirgger continuously depressed. In this latter condition, the weapon can automatically and continuously repeat the loading operation and the firing of the cartridges until these are exhausted from the magazine or until the pressing of the trigger has ceased.
Accordingly, such portable automatic weapons, generally, include mechanisms that comprise at least one hammer or striking means, a trigger and a pawl, the three elements interacting for the individual firing operation, a rapid fire level cooperating with the hammer and with the firing pin, so as to obtain the rapid fire operation while keeping the trigger continuously depressed, and, finally, a fire selecting means for determining the mode of firing of the weapon. With these mechanisms, however, it is not possible to have an efficient and proper control of the firing operation in the rapid fire mode, because even if to keep the trigger is depressed for only an additional fraction of time, in excess of the desired one, a totally different number of shots will be fired. Hence, there is a need to provide the portable automatic weapons also with means for controlling and limiting the rapid fire mode of the weapon, to have a more suitable, versatile and reliable utilization of the weapon itself.